The present invention relates to a powder feeding device for spray coating powder, hereafter spraycoating powder feed apparatus.
The patent documents DE 103 53 968 A1; U.S. Pat. No. 6,508,610 B2; US 2006/0193704 A1 and JP 09071325 A disclose coating powder feeding pumps which by means of a partial vacuum aspirate a powder dose into a powder chamber and then expel said dose from said chamber by means of compressed air. In said documents the (partial) vacuum is produced by a vacuum source and the compressed air by a compressed air source. The German patent document DE 101 45 448 A1 discloses a powder pump fitted with a powder chamber wherein the vacuum is produced by a suction plunger bounding the powder chamber. The European patent document EP 0 412 289 B1 discloses a powder pump in the form of an injector.
Electrostatic powder spraycoating equipment is known from EP 0 412 289 B1. Other powder spraycoating equipment is known from DE 42 39 496 A1 and U.S. Pat. No. 3,918,641.